(Chuckle) - Vic, it's not one of the MFJ "Antenna Tuners" rated at d-c input to the rig's finals instead of RF output. (I'm sure MFJ realizes that confuses most of today's Hams, most of whom don't know what d-c input means and those who do never think about it, but MFJ seems to feel that they are stuck with the legacy, Hi!)
I have one of those dummy loads (MFJ-264) and it's perfect for what it was intended to do. There's a bold chart on the end showing that it can handle 1.5 KW for about 9 seconds key down. That time extends at lower powers: 500 watts for a bit over 30 seconds and 100 watts for at least 10 minutes (600 seconds). Maybe Bill has a different model or he misread the chart. I've had the 264 for a number of years. The fellow asking the question didn't say what he was using for a load, but if it was an overheating dummy I'd suspect that: 1) He'd see the SWR reported by the KPA500 rising as the load overheated, and 2) he'd smell it as the dummy load became a space heater! Still Bill's suggestion is a good one. Leave no stone (smoking or otherwise) unturned, Hi! 73, Ron AC7AC -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Vic K2VCO Sent: Friday, January 27, 2012 10:43 AM To: [email protected] Subject: Re: [Elecraft] KPA500 Power Output Of course! It's rated in MFJ WATTS. One regular watt = about 10 MFJ watts. Elecraft is one of the few companies making products rated in real watts. On 1/27/2012 10:21 AM, Bill Gerth wrote: > Bert, > > In addition to the other suggestions you received, I'd suggest that > you make sure your dummy load is capable of this kind of key-down > power for that amount of time. I have an MFJ Dummy Load that is > called a 1.5KW Dummy Load but the chart on the back panel shows it is > only capable of around 120 watts for 60 seconds. It can only handle > 1.5 KW for less than 10 SECONDS. Some fan-cooled or oil-cooled dummy > loads might be OK for 500 watts of key-down for 1 minute, but my air- > cooled 1.5 KW Dummy Load is NOT. The non-inductive resistor gets very > hot and begins to smell even after relatively short key-down periods. > Your power change might be due to the dummy load changing its > effective resistance due to heating. > > Just a thought. > > 73, > > W4RK - Bill Gerth > Jefferson City, MO > [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
